The present invention relates generally to switch actuators for use in keyboards and the like, and more particularly to movable keys having a backlighting function.
Generally described, a wide variety of keyboards are utilized for data entry terminals and remote control terminals. Typically, the keys of the keyboards correspond to a particular numeral or operation. Often these keys are complex in construction and operate not only to make switch contact, but to provide an operator with a tactile sensation or feedback, whereby the operator is assured of having made switch contact. Such switches employ a wide variety of structures ranging from spring loaded assemblies to dome-type switch elements to provide this tactile feedback signal.
Many of such keyboards also provide backlighting of the individual keys, so that the keyboard may be used at certain times, for example, to indicate when the key has been properly depressed, to indicate the status of a function controllable by the key, or in a darkened environment. Commonly, backlighting is provided by a plurality of light emitting diodes (xe2x80x9cLEDsxe2x80x9d) associated with each of the keys. However, the use of LEDs as the source of illumination has led to many deficiencies in the prior art. For example, the placement of the LEDs within the keys or the number of LEDs utilized to illuminate each key has caused significant problems, such as intensely illuminated areas and non-uniform illumination, i.e. hot spots, which are unacceptable in modern backlighted keys. Additionally, the number of LEDs utilized to illuminate each key has caused greater energy consumption by each key, which is again unacceptable in modern backlighted keys.
The present invention is directed to a key assembly having a backlighting function that provides a more uniform illumination of the keys, reduces the presence of hotspots, and lowers the energy consumption of the key.
In accordance with aspects of the present invention, a backlit key assembly is provided. The key assembly includes a key having a light translucent region. The key is axially movable along a longitudinal axis of the assembly. The key assembly also includes a base and a key support structure operably connected to the base. The key support structure is operable to guide the key when the key is axially movable along the longitudinal axis of the assembly. A switch operable to generate a signal corresponding to the axial movement of the key is provided. The switch includes an opaque member. The key assembly further includes an illumination source mounted to the base in substantial alignment with the opaque member. The illumination source is operable to provide light for backlighting the key assembly through the light translucent region.
In accordance with another aspect of the present invention, a backlit key assembly is provided. The key assembly includes a key having a proximal surface and a distal surface with a translucent region. The key is movable between a non-depressed position and a depressed position along a longitudinal axis of the key assembly. The key assembly also includes a base and a key support structure operably connected to the base. The key support structure is operable to support the key between the non-depressed and depressed positions along the longitudinal axis of the key assembly. A switch disposed adjacent to the base is also provided and is operable to generate a signal when the key is moved proximally to the depressed position. An opaque portion of the switch is in substantial alignment with the translucent region. The key assembly further includes a light source coupled to the base in substantial alignment with the opaque portion, wherein the key assembly is operable to permit light from the light source to pass through the translucent region.
In accordance with still another aspect of the present invention, a backlit key assembly is provided. The key assembly includes a key having a light translucent region. The key is movable between a non-depressed position and a depressed position. The key assembly also includes a circuit board and a key support structure operably connected to the circuit board. The key support structure slideably receives the key. An actuation layer is provided that includes a depressible member that extends outwardly from the actuation layer. The depressible member includes a first electrical contact. The key assembly further includes a switch layer disposed between the actuation layer and the circuit board. The switch layer includes a second electrical contact in overlapping alignment with the first electrical contact. An illumination source is mounted to the circuit board in substantial alignment with the first and second electrical contacts. The illumination source is operable to provide light for backlighting the key assembly through the light translucent region. The first electrical contact contacts the second electrical contact when the key is movable to the depressed position, thereby generating a signal.
In accordance with yet another aspect of the present invention, a backlit key assembly is provided. The key assembly includes a key having a top surface with a light translucent region. The key is movable between a first and a second position when an axial force is exerted on the top surface. The key assembly also includes a base and a key support structure operably connected to the base. The key support structure is operable to support the key between the first and second positions. A switch disposed adjacent to the base is further provided and is operable to generate a signal when the key is in the second position. The switch includes an electrical contact. The key assembly further includes a light source mounted to the base in substantial alignment with the electrical contact and a depressible member disposed adjacent to the switch. The depressible member is operable to maintain the key in the first position when the axial force is not exerted on the top surface of the key, and operable to return the key to the first position from the second position when the force is removed from the top surface of the key.
In accordance with still yet another aspect of the present invention, a backlit key assembly is provided. The key assembly includes a key having a light translucent region. The key is movable between a non-depressed position and a depressed position along a longitudinal axis of the assembly. The key assembly includes a base and a key support structure operable to support the key and adapted to connect the key to the base. A switch is provided that overlays the base and operable to generate a signal. The switch includes an electrical contact. The key assembly further includes an actuator disposed adjacent to the key and extending parallel to the longitudinal axis. The actuator operable to engage the switch when the key is in the depressed position. An illumination source is mounted to the base in substantial alignment with the electrical contact. The illumination source is operable to provide light for backlighting the key assembly through the light translucent region.